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Titolo:
ACTIVATION KINETICS OF AMPA RECEPTOR CHANNELS REVEAL THE NUMBER OF FUNCTIONAL AGONIST BINDING-SITES
Autore:
CLEMENTS JD; FELTZ A; SAHARA Y; WESTBROOK GL;
Indirizzi:
OREGON HLTH SCI UNIV,VOLLUM INST,L474 PORTLAND OR 97201 OREGON HLTH SCI UNIV,VOLLUM INST PORTLAND OR 97201 AUSTRALIAN NATL UNIV,JOHN CURTIN SCH MED RES CANBERRA ACT 0200 AUSTRALIA CNRS,LAB NEUROBIOL CELLULAIRE F-67084 STRASBOURG FRANCE TOKYO MED & DENT UNIV,FAC DENT,DEPT PHYSIOL TOKYO 113 JAPAN
Titolo Testata:
The Journal of neuroscience
fascicolo: 1, volume: 18, anno: 1998,
pagine: 119 - 127
SICI:
0270-6474(1998)18:1<119:AKOARC>2.0.ZU;2-S
Fonte:
ISI
Lingua:
ENG
Soggetto:
METHYL-D-ASPARTATE; EXCITATORY SYNAPTIC CURRENTS; CULTURED HIPPOCAMPAL-NEURONS; CA3 PYRAMIDAL CELLS; GLUTAMATE RECEPTORS; TIME-COURSE; NMDA RECEPTORS; ACID RECEPTORS; STRUCTURAL DETERMINANTS; KAINATE RECEPTORS;
Keywords:
GLUTAMATE RECEPTORS; AMPA RECEPTORS; CYCLOTHIAZIDE; HIPPOCAMPUS; ION CHANNELS; PATCH CLAMP;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
61
Recensione:
Indirizzi per estratti:
Citazione:
J.D. Clements et al., "ACTIVATION KINETICS OF AMPA RECEPTOR CHANNELS REVEAL THE NUMBER OF FUNCTIONAL AGONIST BINDING-SITES", The Journal of neuroscience, 18(1), 1998, pp. 119-127

Abstract

AMPA and NMDA receptor channels are closely related molecules, yet they respond to glutamate with distinct kinetics, attributable to differences in ligand binding and channel gating steps (for review,; see Edmonds et al., 1995). We used two complementary approaches to investigate the number of functional binding sites on AMPA channels on outside-out patches from cultured hippocampal neurons. The activation kinetics of agonist binding were measured during rapid steps into low concentrations of;selective AMPA receptor agonists and during steps from a competitive AMPA receptor antagonist, 6-cyano-7-nitro-quinoxaline-2,3-dione, into a saturating concentration of agonist. Both approaches revealed sigmoidal kinetics, which suggests that multiple agonist binding steps or antagonist unbinding steps are needed for channel activation. A kinetic model with two independent binding sites gave a better fit to the activation phase than models with one or three independent sites. A more refined analysis incorporating cooperative interaction between the two binding sites significantly improved the fits to the responses. The affinity of the first binding step was two to three times higherthan the second step. These results demonstrate that binding of two agonist molecules are needed to activate AMPA receptors, but the two binding sites are not identical and independent. Because NMDA receptors require four ligand molecules for activation (two glycine and two glutamate; Benveniste and Mayer, 1991; Clements and Westbrook, 1991), it may be that some binding sites on AMPA receptors are functionally silent.

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Documento generato il 12/07/20 alle ore 05:49:23